Dr Tsuyoshi Takeuchi Biology︱ direct combat or “warning” signals). These displays finish when the ’ accumulated cost (such as energy depletion), reaches the threshold level. It

is the loser’s Resource Holding Potential Chu/Shutterstock.comBen (RHP) that dictates the end of a contest. A ’s An animals RHP is its ability to “win” resources against their competitor; factors such as body size can aid this. The model has two main assumptions: 1 Resting opponents can have costs point of view: inflicted upon them. Contest or sex recognition? 2 Competitors can distinguish between rivals and others such as partners.

ontest behaviour has been flying object (whether it be a male or It was once thought that the chasing For many years it was thought studied in wildlife for many female butterfly, another , or a behaviour seen in was a that when butterflies chase years. When animals compete, predator) males often fly over and “give war of attrition, however there is much other males, this is a form C it is usually over limited resources such chase.” If the opponent is a conspecific conflicting evidence to this idea. of contest behaviour over as mates, territory or food. Behavioural male, the two males chase each other. territory. However, Dr Tsuyoshi ecologists (those who study an ’s This behaviour was once thought to THE CONFLICTING EVIDENCE Takeuchi from Osaka Prefecture behaviour from the point of view of be contest behaviour, and the main By interrogating the literature, Dr University and his team sought Pair of mating Old World swallowtail Darwinian natural selection) have game theory which stood out was Takeuchi discovered that the butterflies’ to interrogate the literature to butterflies ( machaon). produced countless theories about why the war of attrition model. However, behaviour could be simplified to a see if a more simple and more likely option could be provided. contests begin, why they end, and what butterfly contests conflict with the main model which required less cognitive Their ‘Erroneous Courtship leads to the winner. Contrary to these assumptions of this model. ability on the butterflies’ behalf. Because Dr Takeuchi discovered that the Model’ states that the male theories, butterflies have no weaponry the butterflies lack any weaponry (teeth, butterflies are giving chase and males exhibit unique mating GAME THEORY claws etc), it is unlikely that costs will butterflies’ behaviour could be simplified to distinguish the sex of the patterns, either chasing flying females Game theory is well established within be placed upon a resting opponent. to a model which required less cognitive approaching butterfly. They then or crowding round pupae. In addition, the multiple disciplines, including business However, some species of butterfly test this hypothesis against the males also engage in chasing behaviour studies and animal behaviour. In do engage in “clashes.” Despite this, ability on the butterflies’ behalf. Old World swallowtail (Papilio with other males. The researchers behavioural ecology, it decides which neither butterfly ends up injured. machaon) butterfly. produced a series of theoretical, behaviours will become an Evolutionary Clashes are performed by two flying The Erroneous Courtship Hypothesis. the likelihood that the object is another observational and experimental papers Stable Strategy (ESS). ESS’s are butterflies, meaning that a resting Their model assumes that male butterflies female butterfly. So, the aerial clashes to investigate and understand butterfly the “strongest” behaviours which will opponent is not having costs inflicted seek to discover the sex and species of and chasing may in fact be a result behaviour. The main question they aimed be evident throughout the population. upon him. There is another potential any flying object. They approach the of the erroneous courtship. to answer: “Are butterflies competing They cannot be “cheated” – i.e. cost: . However, it is more likely object and begin to chase it. The chasing for territory when they give chase, outcompeted by other behaviours. that the butterfly which is displaying will either end in copulation or, failure. If the animal being pursued is a female or is their behaviour more a process There are various models which game is more likely to be predated on – either The pursuit will be classed as a failure butterfly and she is receptive, they of sex recognition to aid with courtship?” theory helped to establish – one due to the increased movement alerting either because the object is a male will both alight and the male seeks of them being the war of attrition. predators, or the depletion of energy butterfly, or because it is a completely copulation. The costs spent by males REPRODUCTIVE BEHAVIOUR making it harder to escape. different species altogether. How long depends on factors such as their physical Males of many butterfly species occupy WAR OF ATTRITION the male butterfly chases this object for condition and energy levels. For example, a territory, with no benefit other than War of Attrition states that animals The butterflies also chase both sexes. depends on various factors such as the males with less residual reproductive value to access females. Once they see a will engage in costly displays (either Sex recognition abilities vary between reproductive potential of the male, and will court females for longer (because species. Some butterflies can determine the sex of “pretend” butterflies from a distance, whilst others cannot. There have been no studies which show that males can discriminate from the sexes during aerial encounters. This may be because female butterflies lack strong sex pheromones, or because the poor vision of both the sexes, making it hard to discriminate from a distance.

THE ERRONEOUS Photos showing the male COURTSHIP HYPOTHESIS The Erroneous Courtship Hypothesis assumes Male-male interaction of the Papilio machaon. that male butterflies seek to discover the sex Papilio machaon butterfly In 2016, Dr Takeuchi and his colleagues flying around the female. and species of any flying object. put forward an elegantly simple model:

www.researchoutreach.org www.researchoutreach.org they have less future chance), meaning the chase will be longer. Behind the Research But, why does the butterfly flee the area when the chase has finished? Surely it must be better to wait in pursuit Tsuyoshi Takeuchi of another female? The butterflies’ cognitive abilities are not as intricate as E: [email protected] T: +81-72-254-9413 many mammals. They find it difficult to W: https://www.researchgate.net/profile/Tsuyoshi_Takeuchi distinguish between butterflies and other flying such as bees and wasps. Research Objectives References When sexual recognition is complete and the chase is abandoned, it makes sense to Dr Takeuchi’s research aims to understand insect behaviour, Maynard-Smith, J., Price, G.R. (1973). The logic of escape the territory in case they are being not from the point of view of humans but of that of insects. animal conflict.Nature 246, pp. 5–18. https://doi. preyed upon by a predator. Of course, if org/10.1038/246015a0 you have been consumed by someone Maynard Smith, J. (1974) Theory of games and the evolution else, you will have no more opportunities Detail of animal conflicts.Journal of Theoretical Biology 47, pp. to pass on your genes. 209-221. https://doi.org/10.1016/0022-5193(74)90110-6 Responses of territorial males to each butterfly specimen. Entomological Laboratory Takeuchi, T., Yabuta, S., Tsubaki, Y. (2016). The erroneous THE OBSERVATIONS Graduate School of Life and Environmental Sciences courtship hypothesis: do insects really engage in aerial In a recent publication, Dr Takeuchi interaction recorded. The males chased 1 Fresh male; a specimen killed within Osaka Prefecture University wars of attrition? Biological Journal of The Linnean Society, tested the robustness of the erroneous both females, males and other insects. 3 hours before the experiment. 1-1 Gakuencho, Nakaku 118, pp. 970-981. https://onlinelibrary.wiley.com/doi/ courtship hypothesis by investigating However, the female chase is the only 2 Fresh female; prepared the same. Sakai, Osaka full/10.1111/bij.12770 the sex recognition abilities of the Old one that resulted in copulations. The 3 Treated male; a specimen soaked 5998531 Japan Takeuchi, T. (2017). INVITED REVIEW: Agonistic display World swallowtail (Papilio machaon). interactions between butterflies (both in chloroform for 24 h to remove or courtship behavior? A review of contests over mating The swallowtail is one of the most male and females) lasted longer than the chemicals, and then rinsed with fresh Bio opportunity in butterflies.Journal of Ethology, 35(3), pp. 3-12. incompatible species with the hypothesis: interactions between male butterflies and chloroform for 24 h. Dr Takeuchi received his PhD from Kyoto University in 2006. https://link.springer.com/article/10.1007/s10164-016-0487-3 male swallowtails perform a typical insects and butterflies of other species. 4 Treated female; prepared the same. His current research at Osaka Prefecture University focuses Takeuchi, T. (2019). Mating behavior of the Old World courtship flight to flying females on insect ecology. swallowtail, Papilio machaon. Science, 70(1), (suggesting the ability of identifying It was thought that chasing was a Males touched fresh female specimens pp. 17-24. https://doi.org/10.1186/s12983-019-0324-y flying females). In addition, males grab form of sex recognition – however, with his legs, and showed typical courtship Takeuchi T., Yabuta, S., Takasaki, H. (2019). Uncertainty about each other with their legs during the one copulation included no chasing flight to them. For the other types of flying conspecifics causes territorial contests of the Old aerial contests over a mating territory as the female allowed copulation specimens, they rarely showed courtship World swallowtail, Papilio machaon. Frontiers in Zoology, (suggesting that they identify flying males almost instantly. Furthermore, the male flight although they approached and, in 16(22). https://frontiersinzoology.biomedcentral.com/ and attack each other). encounters lead to leg grabbing – which many cases, touched them. In addition, Funding articles/10.1186/s12983-019-0324-y could be a form of territorial contest. territorial males reacted longer to fresh JSPS KAKENHI Grant Number JP16K07523, A census route was established in Does this mean that this butterfly males than to fresh females. These results and JP19K06859 Personal Response the study areas (called transects). can distinguish between the sexes? indicate that although territorial males Interactions between organisms which recognise flying females as sexual partners Collaborators occurred within these transects were THE EXPERIMENT by sensing their chemicals, they cannot • Hiroyuki Takasaki Do you think, in time, that different models will be measured. Takeuchi recorded male Could the swallowtail disprove the identify flying conspecific males, and • Shinji Yabuta suggested for most insect behaviour? Will it be difficult to prove or disprove any new theories? versus male interactions, male and erroneous courtship model? Dr Takeuchi continue to gather information on them. • Yoshitaka Tsubaki female interactions, and interactions demonstrated that the swallowtails Do you mean that insect behaviour will be described with other species. They were recorded engage in what seems like territorial In conclusion, males of the butterfly in different manner compared to other animals such as vertebrates? I think so, in some cases. Our interpretation of until either the interactions finished, or behaviours with other males, and regarded conspecific males as something animal behaviour tends to be influenced by our intuition. the organisms left the transect and could courtship flights with the females. If male like a female. In natural male-male I think behavioural ecologists should pay more attention no longer be observed. butterflies can identify the males from interactions, both males are likely to to the constraints in the abilities of animals, and models the females, the erroneous courtship attempt to touch the opponent’s wings, should be constructed based on these constraints. We will In another set of experiments within hypothesis is no longer valid. The which leads to leg grabbing. In this be able to choose better models that are based on simpler the study, he used butterflies reared behaviour in males was measured and experiment, the erroneous courtship assumptions and fit real animal behaviour. in captivity. They were introduced analysed against four different types of hypothesis cannot be disproved. This to males and the behaviours of their butterfly (Takeuchiet al., 2019) study shows that although a certain model may be applicable to most species, we cannot automatically assume the same Dr Takeuchi shows us that it is sometimes is true for the whole Animal Kingdom. Dr Takeuchi shows us that it is sometimes best to think outside the box and critique best to think outside the box and critique the existing literature, to let you see things the existing literature, to let you see in a new light. things in a new light.

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